AstraZeneca has paused an active phase 1 trial of AZD5991, a direct inhibitor of MCL-1, citing the need to suss out a potential safety issue.
The trial suspension, noted only through ClinicalTrials.gov, came Oct. 19: “The study has been put on hold to allow further evaluation of safety related information,” the brief update said. AstraZeneca did not immediately respond to a request for comment on the trial’s suspension.
The trial was assessing the drug, known as AZD5991, either alone or combined with AbbVie/Roche’s approved blood cancer medicine Venetoclax in relapsed or refractory hematologic malignancies. The drug works by targeting apoptosis, the process of programmed cell death, specifically in blood cancer.
This class has seen safety issues before: Back in 2019, Amgen’s oral small-molecule MCL-1 inhibitor AMG 397 was hit with an FDA halt given a “safety signal for cardiac toxicity.”
And that’s not all: After AMG 397 showed some potential safety issues, Amgen then voluntarily halted enrollment for another early-stage test for AMG 176, given that it too is an MCL-1 inhibitor. Enrollment was, however, then opened back up.
Back in February, work on AMG 397 was stopped, and the focus shifted to AMG 176, which is now in phase 1 for blood cancers and uses an intravenous route of administration.